《ISO-6721-2-2008.pdf》由会员分享，可在线阅读，更多相关《ISO-6721-2-2008.pdf（20页珍藏版）》请在三一文库上搜索。
1、 Reference number ISO 6721-2:2008(E) ISO 2008 INTERNATIONAL STANDARD ISO 6721-2 Second edition 2008-06-01 Plastics Determination of dynamic mechanical properties Part 2: Torsion-pendulum method Plastiques Dtermination des proprits mcaniques dynamiques Partie 2: Mthode au pendule de torsion ISO 6721-
2、2:2008(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading t
3、his file, parties accept therein the responsibility of not infringing Adobes licensing policy. The ISO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General
4、Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given bel
5、ow. COPYRIGHT PROTECTED DOCUMENT ISO 2008 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the addre
6、ss below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2008 All rights reserved ISO 6721-2:2008(E) ISO 2008 All rights re
7、served iii Contents Page Foreword iv 1 Scope . 1 2 Normative references. 1 3 Terms and definitions. 1 4 Principle. 1 5 Test apparatus 3 6 Test specimens. 4 7 Number of specimens 5 8 Conditioning 5 9 Procedure 5 10 Expression of results . 6 11 Precision 9 12 Test report . 9 Annex A (normative) Influe
8、nce of longitudinal force, W 10 Annex B (informative) Damping correction factor, Fd 11 Annex C (informative) Dimensional correction factor, Fc 12 Bibliography. 14 ISO 6721-2:2008(E) iv ISO 2008 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide feder
9、ation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that commit
10、tee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordanc
11、e with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires a
12、pproval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 6721-2 was prepared by Technical Co
13、mmittee ISO/TC 61, Plastics, Subcommittee SC 2, Mechanical properties. This second edition cancels and replaces the first edition (ISO 6721-2:1994), of which it constitutes a minor revision. It also incorporates the Technical Corrigendum ISO 6721-2:1994/Cor.1:1995. Apart from the inclusion of the Co
14、rrigendum (which concerns the last sentence in the first paragraph in Annex C), the main changes are the updating of the references and the correction of ISO 6721-3 to ISO 6721-1 in Subclause 5.6. ISO 6721 consists of the following parts, under the general title Plastics Determination of dynamic mec
15、hanical properties: Part 1: General principles Part 2: Torsion-pendulum method Part 3: Flexural vibration Resonance-curve method Part 4: Tensile vibration Non-resonance method Part 5: Flexural vibration Non-resonance method Part 6: Shear vibration Non-resonance method Part 7: Torsional vibration Non
16、-resonance method Part 8: Longitudinal and shear vibration Wave-propagation method Part 9: Tensile vibration Sonic-pulse propagation method Part 10: Complex shear viscosity using a parallel-plate oscillatory rheometer INTERNATIONAL STANDARD ISO 6721-2:2008(E) ISO 2008 All rights reserved 1 Plastics
17、Determination of dynamic mechanical properties Part 2: Torsion-pendulum method 1 Scope This part of ISO 6721 specifies two methods (A and B) for determining the linear dynamic mechanical properties of plastics, i.e. the storage and loss components of the torsional modulus, as a function of temperatu
18、re, for small deformations within the frequency range from 0,1 Hz to 10 Hz. The temperature dependence of these properties, measured over a sufficiently broad range of temperatures (for example from 50 C to +150 C for the majority of commercially available plastics), gives information on the transit
19、ion regions (for example the glass transition and the melting transition) of the polymer. It also provides information concerning the onset of plastic flow. The two methods described are not applicable to non-symmetrical laminates (see ISO 6721-3, Plastics Determination of dynamic mechanical propert
20、ies Part 3: Flexural vibration Resonance-curve method). The methods are not suitable for testing rubbers, for which the user is referred to ISO 4664-2, Rubber, vulcanized or thermoplastic Determination of dynamic properties Part 2: Torsion pendulum methods at low frequencies. 2 Normative references
21、The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 6721-1:2001, Plastics Determination of dynami
22、c mechanical properties Part 1: General principles 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 6721-1:2001, Clause 3, apply. 4 Principle A test specimen of uniform cross-section is gripped by two clamps, one of them fixed and the other connected
23、to a disc, which acts as an inertial member, by a rod. The end of the specimen connected to the disc is excited, together with the disc, to execute freely decaying torsional oscillations. The oscillation mode is that designated IV in ISO 6721-1:2001, Table 2, and the type of modulus is Gto as define
24、d in ISO 6721-1:2001, Table 3. The inertial member is suspended either from the specimen (method A, see Figure 1) or from a wire (method B, see Figure 2). In the latter case, the wire is also part of the elastically oscillating system. -,-,- ISO 6721-2:2008(E) 2 ISO 2008 All rights reserved Key 1 up
25、per (fixed) clamp 4 lower (movable) clamp 2 temperature-controlled chamber 5 rod 3 test specimen 6 inertial member Figure 1 Apparatus for method A Key 1 counterweight 5 upper (movable) clamp 2 wire 6 test specimen 3 inertial member 7 temperature-controlled chamber 4 rod 8 lower (fixed) clamp Figure
26、2 Apparatus for method B ISO 6721-2:2008(E) ISO 2008 All rights reserved 3 During a temperature run, the same inertial member can be used throughout the whole run, which results in a frequency decreasing naturally with increasing temperature, or the inertial member can be replaced at intervals by a
27、member of different moment of inertia in order to keep the frequency approximately constant. During the test, the frequency and the decaying amplitude are measured. From these quantities, the storage component Gto and loss component Gto of the torsional complex modulus G*to can be calculated. 5 Test
28、 apparatus 5.1 Pendulum Two types of torsion pendulum are specified for use with this part of ISO 6721: a) the inertial member is suspended from the test specimen and the lower end of the specimen is excited (method A, Figure 1); b) the inertial member is suspended from a wire attached to a counterw
29、eight and the upper end of the specimen is excited (method B, Figure 2). Both types of pendulum consists of an inertial member, two clamps for gripping the specimen (one of which is connected to the inertial member by a rod) and a temperature-controlled chamber enclosing the specimen and the clamps.
30、 For method B, a counterweight and connecting wire are also required. 5.2 Inertial member 5.2.1 General The moment of inertia, I, of the inertial member, which may be made of aluminium, for instance, shall be selected as a function of the torsional stiffness of the specimen, so that the temperature-
31、dependent natural frequency of the system lies between approximately 0,1 Hz and 10 Hz. When testing standard specimens (see 6.2), a moment of inertia, I, of about 3 105 kgm2 is recommended if the same inertial member is to be used throughout a run. NOTE For certain materials, e.g. filled polymers, a
32、 value of I of about 5 105 kgm2 may be necessary. If a constant frequency is desired over a broad temperature range, interchangeable inertial members with different values of I may be used, thereby permitting the moment of inertia to be varied in steps of less than 20 %, i.e. the frequency to be cor
33、rected in steps of less than 10 %. When testing standard specimens (see 6.2) at a frequency of about 1 Hz, a maximum moment of inertia of about 3 103 kgm2 is recommended. 5.2.2 Method A (see Figure 1) The total mass of the inertial member, the lower clamp and the connecting rod shall be such that th
34、e weight, W, carried by the specimen is not too high see Annex A, Equation (A.2). 5.2.3 Method B (see Figure 2) The total mass of the inertial member, the upper clamp and the rod must be balanced by a suitable counterweight, so that the longitudinal force, W, acting on the specimen is minimized see
35、Annex A, Equation (A.2). The wire supporting these parts is part of the elastically oscillating system. 5.3 Clamps The clamps shall be designed to prevent movement of the portion of the specimens gripped within them. They shall be self-aligning in order to ensure that the specimen axis remains align
36、ed with the axis of rotation and ISO 6721-2:2008(E) 4 ISO 2008 All rights reserved the test specimen remains adequately secured over the whole temperature range without distortion occurring, thus allowing the free length of the specimen to be accurately determined. The movable clamp shall be of low
37、mass. The moment of inertia of the whole system (consisting of the movable clamp, the inertial member and the connecting rod) shall be determined experimentally. To prevent heat passing from the specimen out of the temperature-controlled chamber and in the opposite direction, the rod connecting the
38、movable clamp and the inertial member shall be thermally non-conducting. 5.4 Oscillation-inducing device The oscillation-inducing device shall be capable of applying to the pendulum a torsional impulse such that the pendulum oscillates initially through an angle of not more than 1,5 in each directio
39、n for normal materials, or not more than 3 in each direction for low-modulus materials (such as elastomers). 5.5 Oscillation-frequency and oscillation-amplitude recording equipment Optical, electrical or other recording systems may be used provided they have no significant influence on the oscillati
40、ng system. The entire equipment for measuring frequency and amplitude shall be accurate to 1 % (within the transition region 5 %). 5.6 Temperature-controlled chamber See ISO 6721-1:2001, Subclause 5.3. 5.7 Gas supply See ISO 6721-1:2001, Subclause 5.4. 5.8 Temperature-measurement device See ISO 6721
41、-1:2001, Subclause 5.5. 5.9 Devices for measuring test-specimen dimensions See ISO 6721-1:2001, Subclause 5.6. 6 Test specimens 6.1 General See ISO 6721-1:2001, Clause 6. 6.2 Shape and dimensions Rectangular test specimens having the following dimensions are recommended: free length, L: 40 mm to 120
42、 mm, preferably 50 mm width, b: 5 mm to 11 mm, preferably 10 mm thickness, h: 0,13 mm to 2 mm, preferably 1 mm -,-,- ISO 6721-2:2008(E) ISO 2008 All rights reserved 5 Specimens which are rectangular in cross-section but whose thickness and/or width varies along the main axis of the specimen by more
43、than 3 % of the mean value shall not be used. When comparing different materials, the dimensions of the specimens shall be identical. Specimen dimensions differing from the preferred ones (50 mm 10 mm 1 mm) should be chosen to conserve geometric similarity with the preferred specimen shape. Alternat
44、ive specimen shapes may be used (e.g. cylindrical or tubular); in such cases, dimensions and tolerances shall be agreed upon by the interested parties. 6.3 Preparation See ISO 6721-1:2001, Subclause 6.3. 7 Number of specimens See ISO 6721-1:2001, Clause 7. 8 Conditioning See ISO 6721-1:2001, Clause
45、8. If mechanical conditioning of the specimen is required, the specimen shall be twisted through an angle greater than 5, but less than 90 in both directions about the torsional-test axis and returned to its normal position. 9 Procedure 9.1 Test atmosphere See ISO 6721-1:2001, Subclause 9.1. 9.2 Mea
46、surement of specimen cross-section See ISO 6721-1:2001, Subclause 9.2. 9.3 Mounting the test specimens Clamp the test specimen between the upper and lower clamps. The longitudinal axis of the test specimen shall coincide with the axis of rotation of the oscillating system. Any misalignment of the sp
47、ecimen will cause lateral oscillations that will interfere with the normal oscillation process. After clamping the test specimen, measure the distance between the clamps (the free length L) to 0,5 %. When setting up the oscillating system in the chamber, check to make sure that the test specimen is
48、not stressed. After assembling the oscillating system complete with test specimen, and checking its alignment, start the heating or cooling (see 9.4). 9.4 Varying the temperature See ISO 6721-1:2001, Subclause 9.4. ISO 6721-2:2008(E) 6 ISO 2008 All rights reserved 9.5 Performing the test Start the f
49、ree oscillations by setting the pendulum (5.1) in motion using the oscillation-inducing device (5.4). Record the oscillation frequency and the oscillation amplitude as it decays. Check that no amplitude decay is caused either by friction between moving and fixed parts of the apparatus or non-linear behaviour of the material under test (see ISO 6721-1:2001